Of isomaltose

Separation of isomaltose from high sugar concentrated enzyme reaction mixture by dealuminated beta-zeolite. Sep. Purif. TechnoL, 38,129. 

Scheme 8.—Synthesis of Isomaltose (8) on a Light-sensitive, Solid Support ((P)).

B-512F Dextransucrase has also been used in conjunction with endodextranase to produce a product with a high content of isomaltose and D-fructose (24). The D-fructose can be removed by a Ca-cation exchange resin, giving an isomaltose syrup. The isomaltose can then be catalytically reduced to isomaltitol, which is sweet and of low caloric value. 

Further findings relevant for the establishment of the chemical nature of enzymatic catalysis and technical apphcation followed within rather short time. Croft-Hill performed the first enzymatic synthesis, that of isomaltose, in 1898, allowing a yeast extract (df-glycosidase) to act on 40% glucose solution (Sumner and Somers, 1953). In 1900 Kastle and Loevenhart found that the hydrolysis of fat and other esters by lipases is a reversible reaction and that enzymatic synthesis can occur in a dilute mixture of alcohol and acid (Sumner and Myiback 1950). This principle was utilized for the synthesis of... 

Other disaccharides are the product of the breakdown of larger polysaccharides. Maltose, cellobiose, and isomaltose are all composed of glucose residues (see Figure 2). Maltose and isomaltose both contain a-glucoses in a(l—>4) linkages in the case of maltose, and in a(l—>6) linkages in the case of isomaltose. Maltose results from the hydrolysis of starch, and isomaltose from the hydrolysis of dextrans. Cellobiose is composed of /3-glucose oc-... 

A major problem during the 1970 s with commercial glucoamylase products was the presence of a contaminating enzyme which formed di-and trisaccharides with alpha 1-6 linkages. Thus, relatively high levels of isomaltose and panose were observed which were much higher than predicted by recombination via glucoamylase reversion. 

In principle, several routes exist for enzymatic isomaltose synthesis. With respect to cost-effectiveness it is obvious that one should use substrates like sucrose or starch that can be exploited by dextransucrase (EC 2.4.1.5) or glucoamylase (EC 3.2.1.3), respectively. However, in both cases, isomaltose represents a side product which is released only in small proportions next to dextran or glucose as main products. Realization of higher yields requires extensive time and effort with respect to engineering of reaction and catalyst design. Based on kinetic investigations dextransucrase has been chosen for the production of isomaltose with sucrose as the substrate, and glucose as an acceptor (see Sect. 2.1). 

For the separation of the loaded zeolite from the product suspension, centrifugation can be used. The interparticle void volume of zeolite consists of a solution that contains the substrates and fructose as a byproduct. Therefore several washing steps are required. The more washing effort applied, the higher the resulting purity of isomaltose (Fig. 16). However, a rise in isomaltose purity comes along with lower product yields. 

Ergezinger M, Bohnet M, Berensmeier S, Bucholz K (2006) Integrated enzymatic synthesis and adsorption of Isomaltose in a multiphase fluidized bed reactor. Eng Life Sci 5 1-8... 

Holtkamp M, Erhardt FA, Jordening H-J, Scholl S (2009) Reaction-integrated separation of isomaltose by ad- and desorption on zeolite. Chem Eng Process 48 852-858... 

The pea lectin binds a-D-Iinked D-glucobioses, but not /3-D-linked disaccharides (except for gentiobiose, which has one-eleventh the inhibitory effect of isomaltose). Like con A, it interacts with 2-0-(2-acetamido-2-deoxy-/3-D-gIucopyranosyI)-D-mannose, suggesting that it may be capable of binding to glycoproteins containing internal 2-0-substituted a-D-mannopyranosyl residues.210... 

---